The goal of the proposed study is to investigate the role of social support and personality factors in the psychological adjustment, health behaviors, and physical functioning of coronary artery bypass graft (CABG) patients. Gaining an accurate understanding of the factors which predict recovery following CABG surgery is crucial, given that its express goal is to improve quality of life, rather than to necessarily lengthen life. Several studies have demonstrated the positive impact that social support has on psychological and physical outcome in CABG patients. The purpose of the present application is to investigate the mechanism of social support. Specifically, we will assess emotional versus instrumental support in order to determine the active components of social support. In addition, we will investigate the role of social support in mediating the personality characteristics of hostility and optimism, both associated with psychological and physical functioning following surgery in previous studies. We propose a longitudinal design, including a pre-operative assessment, an assessment prior to discharge from the hospital, and follow-up assessments at three and six months following discharge. One hundred CABG patients will be recruited. Subjects will not be excluded on the basis of age, sex, or disease severity, as the impact of these factors will be investigated statistically. Spouses of patients who are married (or cohabitating for at least six months) will also be recruited for participation. Patients (and spouses) will complete questionnaire measures of demographic and medical information, psychological adjustment, social support (both a general measure and one specific to surgery), personality characteristics, health behaviors, and quality of life. The following questions will be addressed using hierarchical multiple regression. First, what is the mechanism of social support's affect on CABG patients' psychological adjustment, health behaviors, and physical recovery (measured at 3 and 6 months post-operatively)? We will investigate the relative importance of emotional versus instrumental support as the potential mechanism of action. Second, does social support mediate the relationship between personality characteristics (hostility and optimism) and 1) psychological adjustment or 2) health behaviors? We predict that social support will partially mediate the effects of optimism for both outcome variables. For hostility, social support will mediate its effects on health behaviors only.